This invention relates to a touch panel and a method for controlling same.
Touch panel frames have recently become widely used in conjunction with video displays such as CRT screens or flat panel displays. One form of touch panel presently being used includes a rectangular frame which mounts in front of the display and which includes a plurality of devices around its perimeter for emitting energy beams and projecting them across the screen to an oppositely positioned beam detector. When a stylus or other foreign object blocks one or more of the beams, an analyzing circuit senses the blockage and calculates the location of the blockage on the surface of the screen. This information is then transferred to a host computer which controls the video display. Thus, it is possible to use a stylus, or even a person's finger, to write or mark on the screen.
Different kinds of energy beams have been utilized, but infrared beams are commonly used. One problem with the utilization of infrared beams is that ambient light can sometimes interfere with the ability of the system to sense blockage of the particular beams being projected across the screen.
One way of preventing the interference of ambient light is to cause the infrared beams to be modulated at a particular frequency so that the electronic circuitry can analyze and sense the blockage of a beam as it is being projected across the video screen.
An example of such a device is shown in U.S. Pat. No. 4,868,912. However, the device shown in this patent modulates the infrared beam with an LED modulator, which is a separate electronic device incorporated into the circuit. The LED modulator generates an analog sine wave signal which is later converted to a digital signal by other components within the device.
Therefore, a primary object of the present invention is the provision of an improved touch panel and method for controlling the same.
A further object of the present invention is the provision of an improved touch panel which utilizes a central processor for modulating the generation of the various infrared beams, rather than utilizing a separate electrical component for modulating the beams as is the case in the above U.S. Pat. No. 4,868,912.
A further object of the present invention is the provision of a touch panel and method for controlling same which permits the easy adjustment or variance of the particular manner in which the light beams are modulated.
A further object of the present invention is the provision of an improved touch panel and method for controlling same which utilizes simpler electrical circuitry and fewer electrical components than in prior devices.
A further object of the present invention is the provision of an improved touch panel which uses a central processor capable of initially generating a digital modulated signal for modulating the energy beam.
A further object of the present invention is the provision of an improved touch panel which is economical to manufacture, durable in use, and efficient in operation.